"I want to use my own smartphone in Japan, and I heard eSIMs are convenient, but the setup seems difficult..."
"What if I arrive at the airport and can't connect to the internet?"
If you're planning a trip to Japan, do you have these concerns?
Many people land on our website after searching "how to use esim in japan." They want to know more than just where to buy an eSIM; they want the specifics on "how to actually set it up and use it on my own phone."
In this article, we provide a complete step-by-step guide (for iPhone/Android) on how to use an eSIM in Japan and explain the "smart way to choose an eSIM" to avoid connectivity troubles.
Choosing an eSIM for Japan: Why "Native Connection" is Essential
Before diving into the setup, here is a critical warning. Many travelers who use popular global eSIM apps (like Airalo) encounter issues like "slow internet speeds" and "inability to use local payment apps."
This happens because those eSIMs use a "Roaming Connection." To have a smooth experience in Japan, the correct choice is an eSIM with a "Native Connection" that connects directly to Japanese carriers.
The Crucial Difference Between "Native" and "Roaming"
Why does the connection type matter so much? Because the "data route" is completely different.
| Feature |
Native Connection in Japan (e.g., CDJapan) |
Overseas Roaming Connection (Typical Global Apps) |
| Data Route |
Completed within Japan (Direct Flight)
Data takes the shortest route, resulting in ultra-fast speed. |
Routed Overseas (Connecting Flight)
Data travels Japan → Hong Kong/Europe → Japan, slowing down the connection. |
| Response Speed (Ping) |
Fast (Low Latency)
Smooth browsing. |
Slow (High Latency)
Noticeable delay. |
| IP Address |
Japanese IP
All Japanese apps and sites work as usual. |
Foreign IP
Japan-exclusive services are blocked. |
Three Major Problems with Roaming eSIMs (The Downsides)
While roaming eSIMs are often cheap, you must understand the following disadvantages:
- 1. Severe Lag (High Latency)
Since data is routed through overseas servers, things like Google Maps loading or video calls may lag. This causes significant stress when you need to look something up quickly during your trip.
- 2. Inability to Use Japan-Exclusive Apps and Services
Your phone is recognized as being "overseas." Therefore, payment apps, Japanese streaming services, reservation sites for places like Tokyo Disney Resort, and some free Wi-Fi registration screens may not work.
- 3. Excessive Battery Drain
Roaming connections frequently search for the optimal partner network (handover), which tends to drain your smartphone's battery faster than usual.
The eSIMs offered by Japanese companies solve all these problems. Since they connect directly to the communication carriers in Japan, there is no latency, and no websites or apps are blocked.
Why not use an eSIM that provides a native connection to Japan's largest network, Docomo?
Reliable, High-Speed, Low Price
CDJapan Rental eSIM
Preparation: What to Check Before Purchasing Your eSIM
To avoid panicking upon arrival in Japan, make sure to complete these checks and preparations before you leave.
Check 1: Confirm Your Phone is SIM-Unlocked
This is the most crucial step. If your smartphone was purchased through a specific carrier (AT&T, Verizon, etc.), it must be SIM-unlocked. You cannot use an eSIM if your phone is SIM-locked.
Check 2: Confirm Your Device is eSIM Compatible
It's easy to check if your phone is eSIM compatible:
It's easy to check if your phone is eSIM compatible:
- Open your phone's dialer.
- Dial *#06#.
A screen with information will appear. If your phone is eSIM-compatible, you'll see an EID number in the list.
Please note that on some phones, the list may not be immediately obvious. Ensure you scroll all the way down, as the EID number might also appear as 'EID 2'.
Purchasing Your eSIM
Purchase your eSIM plan for Japan. Immediately after purchase, you will receive an email with setup instructions, or they will be available on the website. The QR code provided in the setup guide is scanned by the smartphone you intend to use to install the eSIM. We strongly recommend purchasing a local connection eSIM provided by a Japanese company. You'll have access to many unique Japanese content and services, so avoid the roaming type and choose a Japan-based eSIM service.
Japan eSIM
Installation Steps (iOS / Android)
We recommend performing the setup at home before you leave, or in an airport Wi-Fi environment. While you can set it up at the Japanese airport's Wi-Fi, you likely have the most time to do it before departure.
For iPhone (iOS) Users
- Open Settings > Cellular (Mobile Data).
- Tap "Add eSIM".
- Select "Use QR Code" and scan the QR code you prepared.
- Follow the on-screen prompts. For the eSIM Label, choose a name you'll easily recognize, like "Travel" or "Japan."
- Important: If you are not in Japan yet, keep this new line "OFF." Keep your default line (home number) as your primary line for now.
For Android Users
- Open Settings > Network & internet > SIMs.
- Press the "+" (Add) button and proceed to "Download a SIM?"
- Scan the QR code to start the download.
- When asked if you want to use this SIM after installation, select "No (Do not use)" for now.
What to Do Upon Arrival in Japan
When you land at the Japanese airport, it's time to connect!
Step 1: Switch the Line
- Open the Settings screen and turn "ON" the "Japan eSIM" line you installed.
- Change the "Cellular Data" designation to "Japan eSIM."
- For your original home line, ensure that Data Roaming is "OFF" to prevent high charges (you can keep the line itself ON to receive calls/texts).
Step 2: Perform APN Setup
For iPhone Users:
If the connection uses a Japanese carrier (like Docomo or KDDI), profile installation may be required.
- Connect to the airport's free Wi-Fi.
- Using the link in your purchase email or the QR code in the manual, download the "Configuration Profile (APN Profile)."
- Tap the "Profile Downloaded" message that appears at the top of Settings, and install it. This should connect you.
For Android Users:
Manual entry may be required.
- In the SIM settings screen, look for "Access Point Names (APNs)."
- Press "+" to create a new APN and enter the details exactly as specified in the manual (e.g., Name=CDJapan, APN=vmobile.jp, etc.).
- Save and select the newly created APN.
Tethering / Hotspot Functionality
If you plan to use your smartphone's tethering feature to connect other devices to the internet, you must complete the APN setup.
Troubleshooting: What If My eSIM Isn't Working in Japan?
Solutions if you see "No Service" or have an antenna signal but no internet connection:
- Have you restarted?: It's basic, but restarting your phone often fixes connection issues after configuration changes.
- Are old profiles remaining?: If you've used other travel SIMs before, old profiles (APN settings) might be interfering. Go to Settings > General > VPN & Device Management and delete any old profiles.
eSIMs using a roaming connection must have the roaming feature activated.
However, be aware of the potential for slow connection speeds and the inability to use Japan-specific services when using a roaming eSIM.
A Smooth Trip Starts with the Right Preparation
The procedure for using an eSIM in Japan is very simple once you understand it:
- Confirm you have a SIM-unlocked device.
- Install the eSIM before you leave.
- Upon arrival, switch the line and perform the necessary APN setup.
Most importantly, choose a "high-quality connection" that justifies the setup effort.
Since CDJapan Rental eSIM is a Japanese service, it is recommended for its stable connection and low price.
Are you ready? Find the best plan for you using the link below:
View CDJapan Rental eSIM Plans
